{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Valid code"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stderr",
     "output_type": "stream",
     "text": []
    },
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Hello world\n"
     ]
    }
   ],
   "source": [
    "#include <stdio.h>\n",
    "\n",
    "int main() {\n",
    "    printf(\"Hello world\\n\");\n",
    "}"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "But the kernel will also display compilations warnings and errors if we have some. Let's try to remove the `#include <stdio.h>` statement, which if necessary for `printf` to work."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Code generating warnings during compilation"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stderr",
     "output_type": "stream",
     "text": [
      "/var/folders/31/qct57s856n5f0b2r4tgbmn1c0000gn/T/tmp0Qan0v.c:2:5: warning: implicitly declaring library function 'printf' with type 'int (const char *, ...)' [-Wimplicit-function-declaration]\n",
      "    printf(\"Hello world\\n\");\n",
      "    ^\n",
      "/var/folders/31/qct57s856n5f0b2r4tgbmn1c0000gn/T/tmp0Qan0v.c:2:5: note: include the header <stdio.h> or explicitly provide a declaration for 'printf'\n",
      "1 warning generated.\n"
     ]
    },
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Hello world\n"
     ]
    }
   ],
   "source": [
    "int main() {\n",
    "    printf(\"Hello world\\n\");\n",
    "}"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "You can see that the warning are displayed, but the code is still executed."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Code generating errors during compilation"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stderr",
     "output_type": "stream",
     "text": [
      "/var/folders/31/qct57s856n5f0b2r4tgbmn1c0000gn/T/tmpw4Kz3c.c:2:5: warning: implicitly declaring library function 'printf' with type 'int (const char *, ...)' [-Wimplicit-function-declaration]\n",
      "    printf(\"Hello world\")\n",
      "    ^\n",
      "/var/folders/31/qct57s856n5f0b2r4tgbmn1c0000gn/T/tmpw4Kz3c.c:2:5: note: include the header <stdio.h> or explicitly provide a declaration for 'printf'\n",
      "/var/folders/31/qct57s856n5f0b2r4tgbmn1c0000gn/T/tmpw4Kz3c.c:2:26: error: expected ';' after expression\n",
      "    printf(\"Hello world\")\n",
      "                         ^\n",
      "                         ;\n",
      "1 warning and 1 error generated.\n",
      "[C kernel] GCC exited with code 1, the executable will not be executed"
     ]
    },
    {
     "name": "stdout",
     "output_type": "stream",
     "text": []
    }
   ],
   "source": [
    "int main() {\n",
    "    printf(\"Hello world\")\n",
    "}"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "You can see that the errors and warnings are shown, but the code is not executed. The retcode is also added to the end of `stderr`"
   ]
  }
 ],
 "metadata": {
  "kernelspec": {
   "display_name": "C",
   "language": "c",
   "name": "c_kernel"
  },
  "language_info": {
   "file_extension": "c",
   "mimetype": "text/plain",
   "name": "c"
  }
 },
 "nbformat": 4,
 "nbformat_minor": 0
}